Method and Apparatus for Identifying Regions of Interest in a Medical Image

1. A method of identifying a region of interest in a medical image of a subject, the method comprising: receiving, through a user interface of a computer, a medical image into said computer, said medical image of the subject comprising a plurality of voxels, with each of said voxels exhibiting an intensity; automatically executing, in said computer, a computerized algorithm stored in the computer to generate a hierarchy of said voxels of said image sorted in order of said intensity, with non-adjacent voxels labeled with a respective label as a local maximum or a local minimum of said intensity according to said hierarchy; receiving, after generating said hierarchy of voxels, a single user entry into said computer via said user interface, the single user entry designating an initial voxel in said image, said designated initial voxel exhibiting said intensity and label; defining, by said computer, for each label, a predetermined relationship of respective intensities of respective voxels by determining a numerical value of the intensity for the designated initial voxel; determining, by said computer, a set of candidate regions of interest in the image by selecting, for each candidate region of interest, a set of voxels from the sorted hierarchy with each voxel in said set of voxels having a numerical value for the respective intensity thereof that is equal to or higher than said numerical value of the intensity for the designated initial voxel, wherein said selecting, by said computer, said set of voxels is performed according to selection criteria requiring each voxel of said set of voxels to be adjacent to another voxel of said set of voxels, and wherein any pair of voxels in said set of voxels is connected by a path of adjacent voxels of the set of voxels; determining, by said computer, a hierarchy among the set of candidate regions of interest according to sorted hierarchy of said intensity; receiving, by said computer via said user interface, a user selection of at least one region of interest from said set of candidate regions of interest; and displaying, at a display device in communication with said computer, said selected at least one region of interest comprised of voxels from said stored hierarchy that respectively exhibit an intensity having the predetermined relationship, defined by the label of the designated initial voxel, to said intensity of said designated initial voxel.

2. The method of claim 1 , the method further comprising: requiring, by said computer, the set to include the designated initial voxel; and selecting, by said computer, the region of interest further includes: i. selecting a subset of the set of voxels, said subset containing those voxels respectively having a numerical value for the intensity thereof that is equal to or higher than the numerical value of the intensity for the designated initial voxel; and ii. selecting any other sets of voxels having a minimum voxel numerical value for the respective intensity thereof that is equal to or higher than the numerical value of the intensity for the designated initial voxel, and having at least one voxel adjacent to a voxel of the subset.

3. The method of claim 1 , the method further comprising: requiring, by said computer, the at least one region of interest selected by the user to include a region of interest closest to the designated initial voxel.

4. The method of claim 1 , wherein each candidate region of interest is associated with a local maximum numerical value for the respective intensity thereof; and selecting, by said computer, the at least one region of interest as at least one region of interest associated with a closest local maximum numerical value to the numerical value of the intensity for the designated initial voxel.

5. The method of claim 1 , the method further comprising: identifying, by said computer, a plurality of sets of voxels of the image, each set associated with a local maximum numerical value for the respective intensity thereof; determining, by said computer, a first set of voxels associated with the local maximum numerical value closest to a numerical value of the intensity for the designated initial voxel; determining, by said computer, a second set of voxels associated with a second local maximum numerical value for the respective intensity thereof; and excluding, by said computer, the second set of voxels from the region of interest.

6. The method of claim 5 , the method further comprising excluding, by said computer, said second set of voxels by: setting, as a maximum boundary of the region of interest, an isocontour through voxels having substantially the same numerical value for said intensity, said isocontour surrounding the first set of voxels.

7. The method of claim 6 , wherein the second set of voxels comprises a voxel having said second local maximum numerical value, and setting the maximum boundary to be an isocontour at a minimum numerical value for said intensity without the isocontour surrounding the voxel having the second local maximum value.

8. An apparatus for identifying a region of interest in a medical image of a subject, the apparatus comprising: a processor having an input configured to receive a medical image of a subject to said processor, said medical image of the subject comprising a plurality of voxels, with each of said voxels exhibiting an intensity; said processor being configured to automatically generate a hierarchy of said voxels of said image sorted in order of said intensity with respective voxels labeled with a respective label as a local maximum or a local minimum of said intensity according to said hierarchy; a user interface in communication with said processor configured to allow a user, after said processor has generated said list of voxels, to make a single entry into said processor that designates an initial voxel in said image, said designated initial voxel exhibiting said intensity and said label; said processor being configured to define, for each label, a predetermined relationship of respective intensities of respective voxels by determining a numerical value of the intensity for the designated initial voxel; said processor being configured to determine a set of candidate regions of interest in the image by selecting, for each candidate region of interest, a set of voxels from the sorted hierarchy with each voxel in said set of voxels having a numerical value for the respective intensity thereof that is equal to or higher than said numerical value of the intensity for the designated initial voxel, wherein said selection of said set of voxels is performed according to selection criteria requiring each voxel of said set of voxels to be adjacent to another voxel of said set of voxels, and wherein any pair of voxels in said set of voxels is connected by a path of adjacent voxels of the set of voxels; said processor being configured to determine a hierarchy among the set of candidate regions of interest according to sorted hierarchy of said intensity; said processor being configured to receive, via said user interface, a user selection of at least one region of interest from said set of candidate regions of interest; and a display device in communication with said processor, said processor being configured to cause said selected at least one region of interest, comprised of voxels from the sorted hierarchy that respectively exhibit an intensity having the predetermined relationship, defined by the label of the designated initial voxel, to said intensity of said designated initial voxel, to be displayed at said display device.

9. A non-transitory, computer-readable data storage medium encoded with programming instructions, said data storage medium being loadable into a processor having an interface, and said programming instructions causing said processor to: receive a medical image of a subject to said processor, said medical image of the subject comprising a plurality of voxels, with each of said voxels exhibiting an intensity; generate a hierarchy of said voxels of said image sorted in order of said intensity with respective voxels labeled with a respective label as a local maximum or a local minimum of said intensity according to said hierarchy; receive, via a user interface, after generating said list of voxels, a manually entered designation of an initial voxel in said image, said designated initial voxel exhibiting said intensity and said label; define, for each label, a predetermined relationship of respective intensities of respective voxels by determining a numerical value of the intensity for the designated initial voxel; determine a set of candidate regions of interest in the image by selecting, for each candidate region of interest, a set of voxels from the sorted hierarchy with each voxel in said set of voxels having a numerical value for the respective intensity thereof that is equal to or higher than said numerical value of the intensity for the designated initial voxel, wherein said selection of said set of voxels is performed according to selection criteria requiring each voxel of said set of voxels to be adjacent to another voxel of said set of voxels, and wherein any pair of voxels in said set of voxels is connected by a path of adjacent voxels of the set of voxels; determine a hierarchy among the set of candidate regions of interest according to sorted hierarchy of said intensity; receive, via said user interface, a user selection of at least one region of interest from said set of candidate regions of interest; and generate a display of said selected at least one region of interest, comprised of voxels from the sorted hierarchy that respectively exhibit an intensity having the predetermined relationship, defined by the label of the designated initial voxel, to said intensity of said designated initial voxel, at a display device in communication with said processor.